1. Field of the Invention
This invention relates to tissue ablation systems. More particularly, this invention relates to simulated operation of an RF generator in tissue ablation system.
2. Description of the Related Art
Cardiac arrhythmias, such as atrial fibrillation, occur when regions of cardiac tissue abnormally conduct electric signals to adjacent tissue, thereby disrupting the normal cardiac cycle and causing asynchronous rhythm.
Procedures for treating arrhythmia include surgically disrupting the origin of the signals causing the arrhythmia, as well as disrupting the conducting pathway for such signals. By selectively ablating cardiac tissue by application of energy via a catheter, it is sometimes possible to cease or modify the propagation of unwanted electrical signals from one portion of the heart to another. The ablation process destroys the unwanted electrical pathways by formation of non-conducting lesions.
U.S. Patent Application Publication No. 2009/0030411 by Werneth et al. describes an ablation catheter in which a thermocouple can be used to measure the temperature local to the thermocouple prior to, during or after the delivery of ablation energy. It is explained that when an ablation is performed, maintaining the tissue at a temperature below a threshold is required. Information recorded from the thermocouple is used to adjust energy delivery or to modify its frequency, based on temperature information analysis.
U.S. Patent Application Publication No. 2011/0218526 provides another example of a thermocouple in an ablation system, which electrodes may be electrically coupled to an output portion of an RF generator, and each thermocouple may be electrically coupled to a feedback portion of the RF generator. A processor accepts an input voltage and produces an output voltage, based on feedback signals from the thermocouples, and then adjusts a duty cycle modulator as well as an amplitude modulator according to the feedback signals.